This invention relates to a process for the production of 1,3-dimethyl-2-imidazolidinone and particularly, to an inproved process for producing 1,3-dimethyl-2-imidazolidinone by reaction of N,N'-dimethylethylene diamine with phosgene.
1,3-Dimethyl-2-imidazolidinone (herein referred to as DMI) is a useful substance as a polar non-proton solvent, particularly, for high molecular compounds such as polyamides, polyvinyl chloride, polyvinyl alcohol, polystyrene, polyurethane and phenol resins. Also, DMI is dissolved in form of complex salts with many of inorganic salts and used as a solvent for various organic reactions.
For producing DMI there have been provided, for example, a process of reacting ethylene diamine with urea and reducing formalin adduct of the reaction products obtained with thickloroacetic acid, formic acid or the like, or an improved process on the above reduction, for example, by hydrogenating under an acid condition with use of noble metal catalysts.
Also, there is already provided a process for the production of DMI by reacting N,N'-dimethylethylene diamine with phosgene (J. Chem. Soc., 1947, 307), however, the yield is very low, less than 20% and therefore, it can not be satisfied industrially.
Furthermore, there is provided an improved process effecting the reaction in an organic solvent such as toluene in the presence of a dehydrochlorinating agent and catalyst with use of trichloromethylchloroformate instead of phosgene thereby obtaining DMI with the yield of 70% or more (Japanese Patent Kokai Koho 53-73561). This process is a roundabout way of once forming trichloromethylchloroformate which is a dimer of phosgene and decomposing it to phosgene again by a catalyst to react with the diamine for the production of DMI.
Accordingly, if DMI could be obtained with a high yield starting directly from phosgene, it would be a cheaper and advantageous production process in a commercial scale.